Field of the Invention
The invention relates to a device for detecting a printing plate position on the cylinder of a rotary printing machine.
For checking in-register feeding or positioning of printing plates, it has generally become known to use a closable electric circuit that is closed due to the engagement of register pins of a clamping bar into measuring notches formed in a printing plate.
It has become known, for example, from the published European Patent Document EP 0 551 976 B1 to provide electrically conductive stops for a printing plate, so that a circuit is closed by the electrically conductive printing plate when the latter is fed or comes to bear precisely against the stops, and accurate positioning of the printing plate is indicated in this manner.
It is an object of the invention to provide a device for detecting a printing plate position that operates without electrically conductive stops.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a device for detecting the position of a printing plate on a plate cylinder of a printing machine, comprising path measuring systems corresponding with one edge of the printing plate.
In accordance with another feature of the invention, the path measuring systems correspond with register punchings formed in the printing plate in a region of register punchings thereof.
In accordance with a further feature of the invention, the path measuring systems, respectively, are formed of a moving or dipping coil or spool and of an armature movable relative to the moving or dipping coil.
In accordance with an added feature of the invention, the path measuring systems, respectively, are disposed at printing-plate stops.
In accordance with an additional feature of the invention, the printing-plate stops are formed as register pins.
In accordance with yet another feature of the invention, the device includes a return spring disposed between the moving coil and the armature.
In accordance with yet a further feature of the invention, an electrical signal is transmittable to a control computer of the printing machine in accordance with the position of the armature relative to the moving coil.
In accordance with a concomitant feature of the invention, the electrical signal is a measure of the position of the printing plate.
Advantageously, path measuring systems based on moving coils are employed as printing-plate detection devices. With the path measuring systems which are used, a high path resolution of about 0.001 mm is realizable.
When a path measuring system is used for each register member, for example, register stop, there being usually two register members for each printing plate, if the printing plate is in a skewed position, the exact extent of the skewed position can be indicated.
The path measuring systems according to the invention are less susceptible to dirt, in comparison with the electrically conductive detection systems heretofore known in the prior art, so that they operate with considerably greater accuracy.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a device for detecting a printing plate position, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: